In a running toy of a radio-controllable system, heretofore, a running body with a receiver and an operating device with a transmitter have respectively been provided with battery-power and power switches.
When such power switch is left in its ON state by accident in the conventional running toy, however, a controlling means upon receiving an external electric wave into a radio-receiver is energized to heat its electrical circuit element. This continued heating state of the electrical circuit element may cause its over-heating and hence danger of accidental fire.
Recently, a battery to be utilized for such type of toys has been improved in its service performance and capacity to such an extent that any mis-operation may cause serious problems of wasteful consumption of the power and the danger of fire accidents.
Accordingly, an object of the inventiin is to provide a power unit useful in a battery-driven toy for detecting a temperature of the heated electrical circuit element of the controlling means upon its energized state through an external signal when the battery power is left in its ON state through the mis-operation and for deenergizing the controlling means when the temperature exceeds a given constant level.